Machine for setting magnetos



July 14, 1942. 1', HANSBARGER 2,289,359

momma FOR SETTI'NG MAGNETOS Filed Sept. 50, 1940- INVENTOR Than-L115 FLl-Iunshuve1" BY ggmaamfilzu ATTORNEY Patented July 14, 1942 FUN-[TED STATES PATENT o l-Flor;

, MACHINE FOR. SETTING MAGNE-TQOS :Thom as.F. 'Hansbarger, Linthicum Heights; 7 [A lication September 30, 19,40, 'SerialNo. 359,049 lClaim. (curt-s11 (Granted under the act of March 3, 1883; as

amended April 30, .1928; 370 O. G. 757) The invention describedherein maybe manufactured andused by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a machine for use in determining when the automatic advance mechanism of a magneto begins to function during operation of the magneto.

It is an object of the invention to provide a simple machine, economical of manufacture, and 1 precise in function to determine and regulate the responsiveness of the automatic advance mechanism of a magneto so provided to the speed at which such a magneto is driven.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawing in which:

The single view constituting the drawing is a diagrammatic view of the machine comprising this invention.

Referring now to the drawing by characters of reference there is shown the bed plate or similar suitable support III of the machine formed to support spaced, upright parallel bearing brackets I I secured thereto in any desirable manner.

A tubular or hollow spindle I2 is journaled in the brackets II and has a pulley I3, hereinafter more fully described, secured on one end por-: tion thereof and a disc I4 secured to the opposite end portion. Preferably the pulley I3 is secured to the left hand end portion of spindle I2 as viewed in the drawing and the disc I4 is formed with a cup shaped cavity I5 directed outwardly of the adjacent bracket II axially of the spindle I2.

Disposed Within the spindle I2 is a draw shaft or tube I6 which is internally threaded adjacent the disc I4, or provided with a collet, to receive the stub shaft ll of a magneto. The draw tube I6 is provided with a suitable knob or crank I9 on its end portion adjacent the pulley I3 to expedite rotation of the tube in drawing the mechanism I8 into snugly seated relation within the cavity I5 in the disc I4. As will be understood longitudinal displacement of the tube I6 relative to the spindle I2 is prevented when the mechanism I8 is in position in the seat I5 by the mechanism itself in one direction and by a suitable shoulder or separate collar on knob I9 in the other direction.

As shown in the drawing the support III is preferably extended to the right of rightmost bracket II and upon such extension supports an induction coil 20 c.omparable'to the self-contained induction .coil of .the ordinary high tension magneto. Conveniently an 'interrupterassembly 2I is secured to the coil 2|] and is so arranged as to be actuable ,by'the interrupter cam 22 carried by the spark advancemechanism I8 being tested as to make and break the circuit through the secondary of the induction coil 20 in the same manner as it would function in an assembled magneto.

The primary of coil 20 is in circuit with a source of power supply 23 and the secondary thereof is connected to the terminals of a suitable air gap in the stroboscope 24 as by the high tension lead 25 and ground as will be understood in the art.

The pulley I3 is formed to receive a suitable driving belt as indicated at 26 and may be driven by either a variable speed motor or by a constant speed motor with variable pulley speeds not shown. As indicated in the. drawing at 21 the pulley is graduated in such manner that the advance of interrupter cam 22 may be read directly from the graduations in terms of degrees of advance of the cam.

In operation of the device the spark advancing mechanism I8 of a magneto to be tested and regulated is removed from the magneto and placed in the cup shaped cavity I5 of the disc I4 after the manner shown in the drawing. The internal threads or collet of the draw tube or shaft "5 are engaged with the stub shaft or sleeve I1 of the mechanism I8 and the tube rotated through means of its knob I9 to secure the mechanism I8 to the disc I4 in snugly seated relation relative to the cup shaped seat I5. An interrupter cam 22 adapted to cooperate with the interrupter assembly 2I is attached to the interrupter cam comprising a part of the original assembly of mechanism I8 and the high tension lead 25 is attached to its terminal on stroboscope 24. The source of power supply 23 is secured to the primary of induction coil 20 and the pulley I3 connected in driven relation to a variable speed motor or motor of constant speed having variable pulley speeds not shown for the sake of clarity. The device is now conditioned for operation and the mechanism I8 is rotated through the pulley I3, spindle I2 and disc I4. Each revolution of the mechanism I8 will cause the interrupter cam 22 through the interrupter assembly 2I to make or break the circuit through the primary of coil 2|] just as it would as if in service on a magneto. As is well known, interruption of the primary circuit of coil 29 will induce a voltage in the secondary suflicient to bridge the air gap in stroboscope 24 thereby causing a spark which will illuminate one of the graduations 21 on the rim of pulley l3. By increasing the speed of pulley 13 until the advancing mechanism l8 begins to function to advance the interrupter cam 22 it can be determined by the apparent change of the illuminated graduation on pulley I3 or the appearance of difierent illuminated graduations how the advancing mechanism I8 functions when in service. By measuring the R. P. M. of spindle l2 when the cam 22 begins to advance and the R P. M. at maximum advance which is read in degrees from the graduations 21 it can be determined whether the advancing mechanism I8 is regulated to function properly. If the mechanism I8 is in a state of maladjustment it is a simple matter to regulate the tension springs or other means governing the operation of the advancing mechanism since the mechanism is freely accessible when demounted from the magneto and mounted in the device of this invention as aforesaid.

The R. P. M. of spindle l2 may be measured by a tachometer or other similar device which may be permanently installed as indicated at 29 if desired.

Having now described what is at present a preferred embodiment of the invention I claim:

In a machine for testing the automatic spark advance mechanism of a magneto so equipped, a support, a tubular spindle journaled on the support for rotation, a pulley secured upon one end portion of the spindle, a disc provided with a cup shaped cavity secured upon the other end portion of said spindle, a draw tube rotatably mounted within the spindle, means on the draw tube adjacent the pulley for rotating the tube, means on the draw tube adjacent said disc for engaging a projecting portion of an automatic spark advance mechanism seated in the cavity of said disc for securing the same to said disc and spindle for rotation therewith, graduations upon said pulley, an induction coil mounted on said support, an interrupter assembly mounted upon the induction coil and adapted to be actuated by an interrupter cam carried on said automatic spark advancing mechanism to interrupt said coil, a stroboscope actuable by said coil to illuminate the graduation on said pulley corresponding to the instant of interruption of said primary.

THOMAS F. HANSBARGER. 

